1. Field of the Invention
This invention relates generally to computer systems, and, more particularly, to a method and apparatus for increasing database availability.
2. Description of the Related Art
Many computer systems employ centralized data storage services to improve efficiency and ease of access. Centralized data storage allows user on various parts of the system simultaneous access to the data. Also, centralized data stores are easier to back up and maintain. One type of computer system that uses centralized data storage is a manufacturing control system, such as a semiconductor manufacturing system. Characteristics of various lots of wafers are tracked. Data in the centralized data store is used to control the flow of lots though the manufacturing process, measure the performance of various tools and processes in the system, and provide statistical data for process control and optimization.
A significant aspect of the manufacturing process is process control. In particular, the fabrication tools and the fabrication environment are routinely controlled to achieve a satisfactory process. Certain operational parameters may be monitored and, when desired, the tool""s operation can be altered to improve the process to yield more or better wafers.
One problem associated with a centralized data store arises directly from its centralized nature. If the computer in the system that manages the data store fails, the entire system may be compromised or shut down entirely. As a result of this single point of failure, a data store outage might result in extended system outages, lost data, or data corruption.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
One aspect of the present invention is seen in a computer system including a first database, a second database, and a data handler. The data handler is adapted to receive a database request, issue a first request to the first database, and issue a second request to the second database. The first and second requests are based on the database request. The data handler is further adapted to receive a first response from the first database, receive a second response from the second database, and ignore one of the first and second responses.
Another aspect of the present invention is seen in a method for increasing database availability. The method includes receiving a database request; issuing a first request to a first database; issuing a second request to a second database, the first and second requests being based on the database request; receiving a first response from the first database; receiving a second response from the second database; and ignoring one of the first and second responses.